Two aspects of the cytotoxic T lymphocyte response to influenza virus will be studied in this proposal. We will examine the heterogeneity and specificity of the cytotoxic T lymphocyte response to specific type A influenza virion antigens with the aim of assessing, from a functional standpoint, the concept that the antigen recognition structures employed by thymus-derived (T) and bone marrow-derived (B) lymphocytes are in part at least shared by the two lymphocyte types. The second part of this proposal deals with viral antigen presentation in the induction of influenza virus-specific cytotoxic T lymphocytes and in the process of target cell sensitization for lysis by influenza virus-specific cytotoxic T lymphocytes. Specifically, we will examine whether the presentation of influenza viral antigens in a specific fashion, i.e., as integral membrane components of the stimulator and target cell cytoplasmic membrane, is required for induction and target cell sensitization.